body {
    margin: 0;
    padding: 0;
}
.mainDiv{
    display: flex;
    width: 100%;
}
.leftDiv{
    width: 16%;
    background: #c0c0c0;
    color: #333;
    font-size: 20px;
    padding: 20px;
}
.rightMain{
    width: 84%;
    height: 1000px;
    background: #fff;
    font-size: 20px;
}